Active immunotherapy with cytokine gene modified tumor (GMT) can induce a tumor specific immune response in experimental animal models and is being applied to human tumors. This proposal is based upon the premise that an effective cell mediated immune response against non-immunogenic spontaneously arising breast tumors can be elicited by active immunotherapy with cytokine gene modified tumor. We have demonstrated in a murine model of breast adenocarcinoma that active immunotherapy with human interleukin 2 (IL-2) GMT cells leads to reduction in tumorgenicity and protection from metastasis development in tumor bearing animals. To apply this therapeutic modality to human use, we have developed methods of isolation of autologous human breast tumor cells. Because the long term culture of human breast cancer cells is difficult, we then developed a novel gene delivery system using cationic liposomes and an adeno associated virus (AAV) based plasmid that leads to high levels of IL-2 expression in primary non cultured breast tumors. We demonstrated that GMT generated by this method of gene transfer could lead to protection from metastasis in our animal model. In addition, we have documented high levels of IL-2 expression from irradiated and cyropreserved gene modified autologous human tumor that can be used for a clinical trial. This preclinical work has resulted in a NIH Recombinant DNA Advisory Committee (RAC) approved phase I protocol to test IL-2 gene modified tumor in patients with metastatic breast cancer. The overall goal of this proposal is to perform a phase I clinical study of active immunotherapy with autologous human IL-2 GMT in patients with breast cancer and provide an analysis of the effectiveness of IL-2 GMT using objective phenotypic and functional markers of immune stimulation. We then propose to develop a phase II clinical trial based on the clinical and biologic data from the phase I study. The proposed clinical trials are facilitated by the Duke Multidisciplinary Breast Clinic, the Duke Bone Marrow Transplant Program and the Duke Oncology Consortium, which are designed to implement clinical trials of novel therapeutic strategies and insures the availability of an adequate number of patients with breast cancer eligible for this study.